This invention pertains for device which control the application of electric energy to heaters that preheat temperature sensitive engine components such as the engine block, the engine oil/transmission and the battery of internal combustion engines before starting after they have been exposed to temperatures that may range to -60 degrees Fahrenheit. Specifically, with a knowledge of the next use time of a vehicle, this invention automatically controls the initiation and duration of engine component heating such that significant savings in energy consumption are realized when compared to existing the methods of preheating engines in cold climates.
The manufacturers of engine component heaters publish recommended combinations of heaters for each available engine size, crankcase oil/transmission type and battery size for private and most commercial vehicles. These heaters are manufactured for the specific application in which heat energy is conducted from the point of component contact with the heater throughout the component with the maximum temperature of the component being reached after approximately five hours of heating. These heaters are also manufactured to standards such that, when properly installed, the maximum temperature of the component being heated does not exceed a temperature which will lead to damage of the component even when heating is continuous or when ambient temperatures exceed those that would normally require heating of the engine components before use.
In the typical daily use cycle of vehicles during the winter in very cold climates, vehicles are not in continuous use for 24 hour periods. Therefore, after a time period in which the vehicles are not in use and exposed to cold ambient temperatures, the engine components of the vehicle will have to be electrically heated before next use. For example, the heaters may be turned on at the end of the day and left on all night so that the components will be warm enough to start in the morning. However, since only a maximum of five hours is typically required to heat the components to their maximum temperature, leaving the heaters on all night wastes a substantial amount of electrical energy even at the lowest expected ambient temperature of the region.
The present art adds a timer or clock between the energy source and the component heaters to reduce energy consumption and engine wear when the desired engine component temperatures are not required until hours or days after the heater is set up. The timer or clock is manually set to supply energy to the component heaters at a time in the future which is long enough before the desired use time of the vehicle to give the user some confidence that the engine components will be heated sufficiently to enable starting. Examples of such clock or timer switched controllers which may be used for engine heaters are contained in U.S. Pat. Nos. 3,213,994 (Hohler), 3,740,564 (Wong) and 3,870,855 (Edlund et al.). These applications manually set the clock or timer to start component heating easily enough so that the user has some confidence that the components will be warmed sufficiently at the time of next use, given the ambient temperature at next use time. The ambient temperature available to the user will normally be a weather bureau forecast which at best is an area estimate which may differ significantly from the local temperature at the time of next use, especially if the weather bureau estimate is for a 24 hour or longer period of time.
In the present art, the length of time that electrical energy is applied to the heaters is an estimate made by the user and not on a computation based on manufactuer's specifications for the components being heated. If the future temperature is milder than predicted, then energy will be wasted because the clock or timer initiates heating sooner than necessary. Or, if the the length of time for heating was not set conservatively, the engine components will not be heated sufficiently at the desired time to allow starting without excessive engine wear.
The present art requires manual adjustment of the start and duration of heating time to account for daily temperature changes. Automatic methods to accomplish engine heating before next use time on a daily basis with confidence that the engine components will be adequately heated are not presently available in the art. Furthermore, the general user does not have access to the manufacturers' heater data nor the knowledge of large object heat conduction dynamics. The random approach to heating engine components employed by the present art leads to the inefficient use of electrical energy, hard starting and/or excessive engine wear during starting.